I get it about the Grip of Death being something that might help a beginner develop some hand strength and some basic ideas of seizing nage.

But after a very short period of that, I worry that the GoD gives nage bad habits, since on the mat they can take for granted that uke is going to hold on no matter what kind of crappy connection they have.

And if you are going to practice the GoD, I really don't think you are doing yourself any good by putting it on, then relaxing. Anybody can squeeze as hard as they can for a couple of seconds. After that, your grip burns out. If you decide that grip strength is a goal of your training you should practice hanging on for awhile.